Study on Non-Planarity in Pancake Coils and its Influence on Magnetic Field

The manufacturing accuracy of high-temperature superconducting pancake coils is a key factor determining the magnetic field performance of high-field and high-homogeneity magnets such as NMR/MRI. This study first obtains the deformation angle of 36 sets of double pancake (DP) coils, in which the angle distribution of the upper half of each DP coil ranges from -3.2 ° to 5.2 ° and in the lower half ranges from -4.4 ° to 3.2 °. Then, using nonparametric Monte Carlo method, combined with electromagnetic simulation and harmonic expansion to analyze 800 sets of magnetic field changes in magnets. The results indicate that non-planarity of DP coil reduces the central magnetic field which is 6.1% to 16.5% lower than the initial central magnetic field, meanwhile the peak-to-peak inhomogeneity typically deteriorates by 2 to 3 orders of magnitude compared to the initial state. This study is aim to quantify the non-planarity of DP coils, briefly analyze the possible causes of non-planarity, and deeply investigate the potential magnetic field effects, laying the foundation for further study on the fundamental causes of this deformation.